1. Field of the Invention
The present invention relates to a displacement measuring instrument, which specifically relates to a displacement measuring instrument having a spindle capable of being manually operated by a lifting lever.
2. Description of Related Art
Conventionally, dial gauges for measuring a thickness of a workpiece by a spindle being manually operated by a lifting lever to measure the displacement thereof have been known (see Japanese Utility Model Publication of Registration No. 3065835, for instance).
As shown in FIG. 6, a dial gauge 40 of the above publication has an upper holder 55A provided on a slidable measurement rod 55 penetrating a center of a display 41. On the other hand, a grip 45 is attached to a side of the display 41 and a lower holder 46 is provided on a holding groove 45A of the grip 45, the lower holder 46 and the upper holder 55A sandwiching a workpiece to measure the thickness of the workpiece.
An end of the measurement rod 55 is in the holding groove 45A and an elastic member 56 is provided between the upper holder 55A and the grip 45 on an end of the measurement rod 55.
A pressing member 50 extending from the display 41 is provided on a side of the display. A part of the pressing member 50 extends from a predetermined opening 41A formed on the side of the display 41 toward the inside of the display to be connected with the measurement rod 55, so that, when the pressing member 50 is pressed, the measurement rod 55 is slid in a direction for the upper holder 55A to move away from the lower holder 46 and, when the pressing member 50 is released, the measurement rod 55 returns to the rest position thereof by the elastic member 56, to press the upper holder 55A onto the surface of the lower holder 46.
In the thickness-measuring dial gauge 40 of the above publication, in order for the pressing member 50 to extend from the side of the display 41 with a part thereof being extended and inserted to the inside of the display 41 and to turn the pressing member 50 within a predetermined range, the opening 41A formed on the side of the display 41 is elongated.
Accordingly, minute dusts and the like enter from the opening 41A into the inside of the display 41, which may undesirably affect on precise measurement. The above problem is caused because the pressing member 50 and the measurement rod 55 are connected inside the display 41.
In order to overcome the above problem, another structure such as a dial gauge 60 shown in FIG. 7 may be proposed. In the dial gauge 60, a measurement rod (spindle) 65 and a pressing member (lifting lever) 70 are connected on the outside of a display (gauge body) 61.
Specifically, a penetrating tap 61A is drilled on a side of the gauge body 61. On the other hand, the lifting lever 70 is swingably supported by a lever support 80 around a pivot axis 81. An attachment hole 70A is formed around the pivot axis 81 of the lifting lever 70 and a penetrating hole 80A corresponding to the attachment hole 70A is formed on the bottom side of the lever support 80. The lever support 80 is attached to the gauge body 61 by inserting a screw 76 from the attachment hole 70A of the lifting lever 70 into the penetrating hole 80A of the lever support 80 and screwing the screw 76 to the penetrating tap 61 A of the gauge body 61.
An elongated groove 70B having an open end is formed on an end of the lifting lever 70. A stopper screw 26 having a head 26A and a rib 26B is attached to a manipulation end 65B of the spindle 65. A circular groove 26C is formed between the head 26A and the rib 26B.
The lifting lever 70 and the spindle 65 are engaged by inserting the elongated groove 70B of the lifting lever 70 into the circular groove 26C of the stopper screw 26 attached to the manipulation end 65B of the spindle 65.
However, when the lifting lever 70 is attached through the penetrating tap 61A drilled on a side of the gauge body 61, minute dust may invade therein before screwing the screw 76 into the penetrating tap 61A or cut powders remaining in the penetrating tap 61A and minute dusts etc. generated when the screw 76 is screwed to the penetrating tap 61A may invade in screwing the screw 76, which may cause trouble in precisely measuring a workpiece. Further, a tool and a lot of work are necessary for fixing the lifting lever 70.